Temperature responsive accelerating pump for an internal combustion engine carburetor

ABSTRACT

An accelerating pump fuel system for an internal combustion engine carburetor. The pump component can be actuated by either a mechanical linkage actuated by a throttle lever or a vacuum motor responsive to intake manifold vacuum. A temperature responsive valve is positioned within the vacuum line between the vacuum motor and the source of intake manifold vacuum and blocks the signal to the vacuum motor at temperatures above a predetermined magnitude. Thus, under warm conditions only the mechanical linkage is responsive to the vehicle acceleration, whereas under cold conditions both the vacuum motor and the mechanical linkage are responsive to vehicle acceleration. By specifically designing the vacuum motor stroke to be longer than the mechanical linkage stroke, the accelerating pump is made to discharge a greater quantity of fuel at cold temperatures and a lesser quantity of fuel at warm temperatures. The temperature sensed by the temperature responsive valve may be engine compartment ambient temperature, intake air temperature, engine coolant temperature, or the like.

United States Patent [1 1 Johnson [75] Inventor; Thomas R. Johnson, AnnArbor,

Mich

[73] Assignee: Ford Motor Company, Dearborn,

Mich.

[221 Filed: Aug. 5, 1974 [21] Appl. Now-191,596

[52] US. Cl. 26l/34 B; 261/34 A [51] Int. Cl. i i FOZM 7/08 {581 Fieldof Search 261/34 A, 34 B [56] References Cited UNITED STATES PATENTS2,355,346 1 1944 Weber 261/34 B 2,62 l ,(129 H952 Moseley 261/34 A2,877,996 [1959 Kinney et al. 261/34 B 2,899.950 {1959 Dcrmond 261/34 B3.3l3 53l [1967 Winkley et 211,. .i 261/34 B 3350,07] H967 Scala, Jr.261/34 A 3,475,994 N969 Kell 261/34 A Oct.7, 1975 Primar Etumtttc'rTimR. Miles Assistant E.\'antiIterGregory N. Clements Attorney, Agent. orFirm-Roger E Erickson; Keith L. Zerschling [57] ABSTRACT An acceleratingpump fuel system for an internal combustion engine carburetor. The pumpcomponent can be actuated by either a mechanical linkage actuated by athrottle lever or a vacuum motor responsive to intake manifold vacuum. Atemperature responsive valve is positioned within the vacuum linebetween the vacuum motor and the source of intake manifold vacuum andblocks the signal to the vacuum motor at temperatures above apredetermined magnitude Thus, under warm conditions only the mechanicallinkage is responsive to the vehicle acceleration, whereas under coldconditions both the vacuum motor and the mechanical linkage areresponsive to vehicle acceleration. By specifically designing the vacuummotor stroke to be longer than the mechanical linkage stroke, theaccelerating pump is made to discharge a greater quantity of fuel atcold temperatures and a lesser quantity of fuel at warm temperatures.

The temperature sensed by the temperature responsive valve may be enginecompartment ambient temperature. intake air temperature, engine coolanttemperature. or the like.

9 Claims, 5 Drawing Figures US. Patent 0a. 7,1975 Sheet 1 of2 3,911,062

PIC-3.2

US. Patent Oct. 7,1975 Sheet 2 012 3,911,062

TEMPERATURE RESPONSIVF. ACCELERATING PUMP FOR AN INTERNAL COMBUSTIONENGINE CARBURETOR BACKGROUND AND SUMMARY OF THE INVENTION Inconventional carburetors the accelerating pump is often a mechanicaldevice to supply extra fuel to the induction passage simultaneously withthe opening of the throttle plate during a vehicle acceleration. It isrecognized that an engine needs a greater amount of fuel to be deliveredby the accelerator pump under cold engine or ambient temperatures thanunder warm engine or ambient temperatures. Furthermore, it is known inthe art to vary the output of an accelerator pump as a function ofengine temperature. See, for example, US. Pat. No. l,98l,969 granted onNov. 27, 1934 to A. M. Prentiss.

This invention provides improved control apparatus for the acceleratingpump of an internal combustion engine carburetor that reduces the lengthof thestroke of the accelerating pump when the temperature sensed by anelement of the control apparatus exceeds a predetermined magnitude. Theinvention alsoprovides apparatus in which the sensed temperature may bethat of the intake air, the engine compartment ambient, engine coolant,or the like. In addition, the invention provides temperature responsiveaccelerating pump apparatus which can be used with existing carburetorstructures without significant modification to basic carburetorstructure and which is generally external to the main body portion ofthe carburetor. Finally, this invention provides accelerating pump fuelsystem which is economical to produce and install and which is reliablein service.

An accelerating fuel pump supply system for an internal combustionengine carburetor constructed in accordance with this invention includesa pump mecha nism having a movable element which when displaced effectsa discharge from the pump into the induction passage of the carburetor.The quantity of fuel discharged from the pump is variable in directrelation to the magnitude of displacement of the movable element of thepump. The movable element may be displaced either by a linkage connectedto a throttle lever or by a vacuum motor.

The vacuum motor is responsive to changes in intake manifold vacuum andis connected by a vacuum passage to a source of intake manifold vacuum.A temperature responsive valve is positioned in the vacuum passage andopens and closes the passage in response to changes in temperature. Thevacuum motor is designed to displace the movable element of theaccelerating pump a greater distance than the maximum stroke resultingfrom actuation of connecting the throttle lever linkage. The temperatureresponsive valve opens when the sensed temperatures are below apredetermined temperature and closed above the predeterminedtemperature; thus, the accelerating pump discharge is in response todisplacement of the throttle lever linkage when temperatures are abovethe predetermined magnitude and in response to the vacuum motordisplacement when temperatures are below the predetermined magnitude.Because the stroke of the vacuum motor is greater than that of thethrottle lever linkage, a proportionately greater quantity of fuel isdischarged to the induction passage of the carburetor when the sensedtemperature is below the predetermined magnitude than when it is abovethe predetermined magnitude.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I of the drawings is a sideelevational view of a carburetor incorporating the invention.

FIG. 2 is a vertical cross sectional view of the accelerator pump andthe vacuum motor portion of the system taken along line 22 of FIG. 3.

FIG. 3 is a top view of the portion of the carburetor shown in FIG. 2.

FIGS. 4 and S are cross sectional views of the thermostatic valvemember.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Carburetor 11 includesa main body or housing 12 having an induction passage 13 and a fuel bowl14 formed therein. An accelerating pump assembly 16 is located adjacentthe fuel bowl. A throttle lever assembly 17 includes a first lever 18secured to throttle shaft 19 and a second lever 21 pivotally mounted onshaft 19 and resiliently biased into abutting engagement with lever 18at point 22. The two levers move as a unit until the second lever 21engages an abutment 23 on the main body 12. At this time, the secondlever 2| remains fixed relative to the carburetor body while furtheropening movement of the first lever 18 results in torsional windup ofspring 24.

The accelerator pump assembly 16 is a conventional diaphragm pumpmechanism and includes a variable volume chamber 27 having one wallformed by a flexible diaphragm element 28. A discharge passage 29 formedin the main body of the carburetor joins the variable volume chamber 27and the induction passage 13. The accelerator pump 16 includes a fuelinlet passage 3] closed by a resilient umbrellatype check valve 32 and asecond relatively small diameter passage 33 that permits vapors todissipate from chamber 27.

A vacuum motor 34 is positioned adjacent the accelerator pump 16 andincludes a flexible diaphragm 36 defining a vacuum chamber 37 and anatmospheric chamber 38. A plunger 39 connects the diaphragm 28 of theaccelerator pump to the diaphragm 36 of the vacuum motor. The plunger 39and the atmospheric pressure sides of the accelerator pump 16 and thevacuum motor 34 are enclosed within a dumbbell-shaped housing 41. Thehousing is attached to the main carburetor body 12 and forms themounting means for the vacuum motor 34.

Flexible diaphragm 28 of the accelerator pump is secured to one end ofthe plunger 39 by a pair of circular elements 42. A compression spring40 acts between the main body 12 and element 42 to bias the plunger tothe left as viewed in FIG. 2. Flexible diaphragm 36 of the vacuum motoris resiliently biased against the opposite, disc-shaped end 43 of theplunger by compression spring 44 and cup 46. The spring 44 is compressedbetween the plunger end 43 and the cover 47 of the vacuum motor. Spring44 exerts a greater force on plunger 39 than spring 40, therefore whenthere is no vacuum present in chamber 37 the plunger 39 is displaced toits rightward most position. A passage 48 communicates the vacuumchamber 37 with a source of intake manifold vacuum.

The accelerator pump 16 includes an actuating lever 51 pivotallyattached by pin 52 to the housing 4]. Lever 51 is interconnected withthrottle lever 21 by a link 53. The accelerating pump lever 51 extendshorizontally through a slot 54 formed in the plunger 39. The lever 51includes a bulging or protruding edge 56 that is engageable with the end57 of the slot 54 so that counterclockwise displacement of the lever 51about the pin 52 as viewed in FIG. 3 causes displacement of plunger 39and flexible diaphragm 28 in a rightwardly direction which in turneffects a discharge of fuel through passage 29.

Positioned in the vacuum passage 48 between the source of intakemanifold vacuum and the vacuum motor 34 is a temperature sensitive valveassembly 58 shown in the drawings as FIG. 4. The valve assembly includesa bimetal disc 59 which above a predetermined temperature sealinglyseats against an O-ring 61 to block the vacuum line 48. As thetemperature drops, the bimetal disc becomes concave and lifts itselffrom sealing engagement with the O-ring 61 to open the vacuum line 48. Acompression spring 62 resiliently urges the periphery of the bimetaldisc into engagement with abutments 63 of the valve housing 64. Anumbrellatype resilient check valve element 66 is centrally mounted onthe bimetal disc and permits a one-way passage of a pressuredifferential through openings 67 of the disc.

OPERATION The accelerating pump fuel system described above isspecifically designed so that a full stroke of the acccl crating pumplever 51 displaces the pump diaphragm 28 a lesser amount than does afull stroke of the vacuum motor 34. The accelerating pump lever strokeis limited by abutment of the accelerator pump lever with housing 4l atpoint 68 or abutment of throttle lever 21 with the stop 23 on thecarburetor housing. Under cold engine operating conditions, a valveassembly 58 is open and the vacuum chamber 37 of vacuum motor 34 is infull communication with the source of intake man ifold vacuum. When asudden acceleration occurs the throttle plates (not shown) of thecarburetor open and the intake manifold vacuum decays. The decrease inthe vacuum signal within the chamber 37 of the vacuum motor permits thecompression spring 44 to move the plunger 39 rightwardly displacing thepump diaphragm 28 rightwardly and forcing a discharge of fuel throughpassage 29 into the induction passage 13 of the carburetor. The umbrellavalve 32 prevents the return of fuel from chamber 27 to the fuel bowl14. The stroke is complete when the element 42 abuts the surface 64 ofthe carburetor housing. Following the acceleration. the intake manifoldvacuum is again restored displacing the plunger 39 leftwardly as viewedin FIGv 2. This left ward displacement of plunger 39 refills theaccelerator pump chamber 27 through orifice 31.

When the temperature sensed by the bimetal disc 59 is above apredetermined magnitude, the disc is sealingly seated against the O-ring61 and the intake manifold vacuum decay is not communicated to the chamber 37 of the vacuum motor 34. The plunger 39 is displaced rightwardlyby movement of throttle lever 21, link 53 and accelerating pump lever51. A maximum or wide open throttle acceleration results in a dischargeof fuel through passage 29 of lesser quantity than that resulting fromfull stroke of vacuum motor 34 because LII movement of accelerating pumplever 51 or throttle lever 21 is limited by abutments 68 or 23,respectively, which stops the plunger 39 before the elements 42 of thepump engage surface 69.

Modifications and alterations will occur to those skilled in the artwhich are included within the scope of the following claims.

1 claim:

1. An accelerating pump fuel supply system for an in ternal combustionengine carburetor. said carburetor including a source of intake manifoldvacuum, an in duction passage, a throttle lever and an accelerating saidaccelerating pump including a movable element displaceable to dischargefuel from said pump into said induction passage. the quantity ofdischarge from said pump being variable in direct relation to themagnitude of displacement of said movable ele ment,

a second lever movable about a pivot axis to displace the movableelement of said accelerator pump.

linkage means interconnecting said second lever and said throttle lever,

a vacuum motor including a movable member connected to the movableelement of said accelerator a vacuum passage communicating said vacuummotor and a source of intake manifold vacuum.

said movable member being displaceable in response to changes in intakemanifold vacuum, means transferring displacement of said movable memberto said movable element.

a temperature responsive valve in said vacuum pas sage to open and closesaid vacuum passage in re sponse to changes in temperature,

a full stroke of said vacuum motor displacing the movable element ofsaid accelerating pump a predetermined distance.

a full stroke of said second lever displacing the movable element ofsaid accelerating pump a distance less than said predetermined distance.

2. A fuel supply system according to claim l,

said temperature responsive valve being open below a predeterminedtemperature and closed above the predetermined temperature.

3. A fuel supply system according to claim I.

abutment means limiting the stroke of said second lever.

4. An accelerating pump fuel supply system for the carburetor of aninternal combustion engine, said carburetor including a source of intakemanifold vacuum. an induction passage. a throttle lever and anaccelerating pump,

said accelerating pump including a first flexible dia phragm member.said diaphragm element forming a wall of a variable volume pump chamber.dis placement of said diaphragm member causing a discharge from saidpump chamber into said induc* tion passage, the quantity of dischargefrom said pump chamber being variable in relation to the magnitude ofdisplacement of said diaphragm member,

a vacuum motor having a second flexible diaphragm member forming a wallof variable volume vacuum chamber.

a rod member attached to both said diaphragm members transmitting thedisplacement of one to the other a vacuum passage communicating saidvacuum chamber and a source of intake manifold vacuum, said seconddiaphragm member being displaceable in response to changes in intakemanifold vacuum.

a temperature sensitive valve in said vacuum passage to open and closesaid passage in response to changes in temperature.

a second lever engageable with said rod member for displacement thereof.

linkage means interconnecting said second lever and said throttle lever.

displacement of said throttle lever causing a corresponding displacementof said rod member.

a full stroke of said vacuum motor displacing the rod member and saidaccelerating pump diaphragm a predetermined distance,

a full stroke of said second lever displacing the movable element ofsaid accelerating pump a distance less than said predetermined distance.

5. A fuel supply system according to claim 4.

said temperature responsive valve being open below a predeterminedtemperature and closed above the predetermined temperature.

6. A fuel supply system according to claim 4,

a housing enclosing said flexible diaphragm members and said rod member,

slot means formed in said rod member and said housing receiving saidsecond lever.

7. A fuel supply system according to claim 4,

abutment means limiting the stroke of said second member.

8. A fuel supply system according to claim 4,

check valve means positioned in said vacuum passage opening toward saidvacuum chamber.

9. A fuel supply system according to claim 4,

spring means urging said rod member and said diaphragm members toward amaximum volume vacuum chamber position and a minimum volume pump chamberposition.

1. AN ACCELERATOR PUMP FUEL SUPPLY SYSTEM FOR AN INTERNAL COMBUSTIONENGINE CARBURETOR, SAID CARBURETOR INCLUDING A SOURCE OF INTAKE MANIFOLDVACUUM, AN INDUCTION PASSAGE, A THROTTLE LEVER AND AN ACCELERATING PUMP,SAID ACCELERATING PUMP INCLUDING A MOVABLE ELEMENT DISPLACEABLE TODISCHARGE FUEL FROM SAID PUMP INTO SAID INDUCTION PASSAGE, THE QUANTITYOF DISCHARGE FROM SAID PUMP BEING VARIABLE IN DIRECT RELATION TO THEMAGNITUDE OF DISPLACEMENT OF SAID MOVABLE ELEMENT, A SECOND LEVERMOVABLE ABOUT A PIVOT AXIS TO DISPLACE THE MOVABLE ELEMENT OF SAIDACCELERATOR PUMP, LINKAGE MEANS INTERCONNECTING SAID SECOND LEVER ANDSAID THROTTLE LEVER, A VACUUM MOTOR INCLUDING A MOVABLE MEMBER CONNECTEDTO THE MOVABLE ELEMENT OF SAID ACCELERATOR PUMP, A VACUUM PASSAGECOMMUNICATING SAID VACUUM MOTOR AND A SOURCE OF INTAKE MANIFOLD VACUUM,SAID MOVABLE MEMBER BEING DISPLACEABLE IN RESPONSE TO CHANGES IN INTAKEMANIFOLD VACUUM, MEANS TRANSFERRING DISPLACEMENT OF SAID MOVABLE MEMBERTO SAID MOVABLE ELEMENT, A TEMPERATURE RESPONSIVE VALVE IN SAID VACUUMPASSAGE TO OPEN AND CLOSE SAID VACUUM PASSAGE IN RESPONSE TO CHANGES INTEMPERATURE, A FULL STROKE OF SAID VACUUM MOTOR DISPLACING THE MOVABLEELEMENT OF SAID ACCELERATING PUMP A PREDETERMINED DISTANCE, A FULLSTROKE OF SAID SECOND LEVER DISPLACING THE MOVABLE ELEMENT OF SAIDACCELERATING PUMP A DISTANCE LESS THAN SAID PREDETERMINED DISTANCE.
 2. Afuel supply system according to claim 1, said temperature responsivevalve being open below a predetermined temperature and closed above thepredetermined temperature.
 3. A fuel supply system according to claim 1,abutment means limiting the stroke of said second lever.
 4. Anaccelerating pump fuel supply system for the carburetor of an internalcombustion engine, said carburetor including a source of intake manifoldvacuum, an induction passage, a throttle lever and an accelerating pump,said accelerating pump including a first flexible diaphragm member, saiddiaphragm element forming a wall of a variable volume pump chamber,displacement of said diaphragm member causing a discharge from said pumpchamber into said induction passage, the quantity of discharge from saidpump chamber being variable in relation to the magnitude of displacementof said diaphragm member, a vacuum motor having a second flexiblediaphragm member forming a wall of variable volume vacuum chamber, a rodmember attached to both said diaphragm members transmitting thedisplacement of one to the other, a vacuum passage communicating saidvacuum chamber and a source of intake manifold vacuum, said seconddiaphragm member being displaceable in response to changes in intakemanifold vacuum, a temperature sensitive valve in said vacuum passage toopen and close said passage in response to changes in temperature, asecond lever engageable with said rod member for displacement thereof,linkage means interconnecting said second lever and said throttle lever,displacement of said throttle lever causing a corresponding displacementof said rod member, a full stroke of said vacuum motor displacing therod member and said accelerating pump diaphragm a predetermineddistance, a full stroke of said second lever displacing the movableelement of said accelerating pump a distance less than saidpredetermined distance.
 5. A fuel supply system according to claim 4,said temperature responsive valve being open below a predeterminedtemperature and closed above the predetermined temperature.
 6. A fuelsupply system according to claim 4, a housing enclosing said flexiblediaphragm members and said rod member, slot means formed in said rodmember and said housing receiving said second lever.
 7. A fuel supplysystem according to claim 4, abutment means limiting the stroke of saidsecond member.
 8. A fuel supply system according to claim 4, check valvemeans positioned in said vacuum passage opening toward said vacuumchamber.
 9. A fuel supply system according to claim 4, spring meansurging said rod member and said diaphragm members toward a maximumvolume vacuum chamber position and a miniMum volume pump chamberposition.